This document discusses wireless security using WPA2. It begins by describing the types of wireless security including open networks, WEP, WPA, and WPA2. It then provides an overview of WPA2, including how it uses AES for encryption and integrity checking. The document compares WEP, WPA, and WPA2 and describes WPA2 authentication in personal and enterprise modes. It details how WPA2 generates keys through a 4-way handshake and uses AES in counter mode for encryption and CBC-MAC for integrity. The document concludes by discussing benefits and vulnerabilities of WPA2 as well as procedures to improve wireless security.
2. CONTENTS
Types of security in WLAN
Comparison of WEP,WPA,WPA2
Evolution of wireless security standards
WPA 2 authentication ,encryption & decryption
Benefits & vulnerabilities
Solutions & conclusion
3. TYPES OF SECURITY IN WLAN
OPEN : No security configured X
WEP : Wired Equivalent privacy X
WPA: Wi-Fi Protected Access
WPA2: Advance Wi-Fi Protected Access
5. WPA2 OVERVIEW
Wi-Fi Protected Access 2
Security standard developed by the Wi-Fi Alliance and is an
implementation of IEEEs 802.11i
Uses Advance Encryption Standard (AES) protocol
AES in Counter-Mode for encryption
AES in Cipher Block Chaining-Message Authentication Code (CBC-MAC)
for integrity checking
9. PERSONAL MODE AUTHENTICATION
Authentication performed between
client and access point
PSK(Pre Shared Key) &
SSID(Service Set Identification) is
used
AP generates 256 bit from plain text
pass phrase
PMK(Pairwise Master Key) is
generated after authentication
10. ENTERPRISE MODE AUTHENTICATION
Based on IEEE 802.1x standard
Authentication performed between
:-
1. Client
2. Access Point
3. Authentication Server
After authentication MK(Master
Key)
Is generated
11. WPA 2 KEY GENERATION
4 way handshake initiated by AP
Confirms clients knowledge of
PMK in personal mode & MK in
enterprise mode
Pairwise Transient Key created
at clients
Fresh PTK is derived at AP
1. Key confirmation key
2. Key encryption key
3. Temporal key
12. WPA 2 KEY GENERATION
Install encryption and integrity
key
Control port are unblocked
13. WPA2 ENCRYPTION
Two Process happens
1. Data encryption
2. Data integrity
AES is used in encryption & authentication is a block symmetric cipher
CCM is new mode of operation for block cipher
Two underlying modes of CCM
Counter mode(CTR) achieves data encryption
Cipher block chaining message authentication code(CBCMAC) to provide data
integrity
14. MESSAGE INTEGRITY CODE(MIC)
IV(Initialization Vector) encrypted
with AES & TK to produce 128
bit result
128 bit result is XOR with next
128 bits of data
Result of XOR is continued until
all IV are exhausted
At end,first 64 bits are used to
produce MIC
Figure :AES CBC-MAC
15. WPA2 ENCRYPTION
Counter mode algorithm encrypts
the data with MIC
Initialize counter for first time or
increment counter.
First 128 bits are encrypted using
AES & TK to produce 128 bits.
XOR is performed on result and first
message block to give an first
encrypted block.
Repeat until all 128 bit of blocks has
been encrypted.
Figure: AES counter mode
16. WPA2 DECRYPTION
It works in reverse using same algorithm for encryption the counter
value is derived.
By using the counter mode algorithm and TK , the
MIC and decrypted
data are found out.
The data is processed by CBC-MAC to recalculate MIC
If MIC does not match then packet is dropped otherwise data is sent
to network stack and to client
17. BENEFITS OF WPA2
Provides solid wireless security model(RSN)
Encryption accomplished by a block cipher
Block cipher used is Advanced Encryption Standard (AES)
IEEE 802.11i authentication and key management is accomplished by
IEEE 802.1x standard
Key-caching
Pre-authentication
18. WPA2 VULNERABILITIES
Cant stand in front of the physical layer attacks:
RF jamming
Data flooding
Access points failure
Vulnerable to the Mac addresses spoofing
19. PROCEDURES TO IMPROVE WIRELESS
SECURITY
Use wireless intrusion prevention system (WIPS)
Enable WPA-PSK
Use a good passphrase
Use WPA2 where possible
Change your SSID every so often
Wireless network users should use or upgrade their network to the
latest security standard released
20. FUTURE SCOPE
A new standard IEEE 802.1W task group(TG) approved in
March,2005
Main Goals
Improve security by protecting the management frames and also being able to
identify
Spoofed management frames normally used to launch DoS attack
22. REFRENCES
Benefits and Vulnerabilities of Wi-Fi Protected Access 2 (WPA2)
Paul
By
Arana
The Evolution of 802.11 Wireless Security INF 795 - Kevin Benton
Wireless LAN Security Issues and Solutions by Pan Feng at 2012
IEEE Symposium on Robotics and Applications(ISRA)
Security Improvements of
IEEE 802.11i 4-way Handshake Scheme
by Xiaodong Zha and Maode Ma 息2010 IEEE